XO-2 is a binary star system about 490 light-years (150 parsecs) away in the constellation Lynx. It consists of two components, XO-2N and XO-2S, both of which host planetary systems.[10]
Star system
This system is unusual in that the stars are not typically referred to as components A & B, but are designated based on their positions in the sky: XO-2N is the northern star and XO-2S is the southern star.
Both of the stars are slightly cooler than the Sun and are nearly identical to each other. The system has a magnitude of 11 and cannot be seen with the naked eye but is visible through a small telescope. These stars are also notable for their large proper motions.[8][9]
XO-2N and XO-2S have a separation of approximately 4,600 AU.[3]
Planetary systems
Two planets were reported to orbit around XO-2S in 2014 using the radial velocity method. One of them is Jupiter-mass and another has a mass comparable to Saturn.[10] A 2024 study found evidence for a third, super-Jupiter mass planet around XO-2S.[11]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥0.26±0.01 MJ | 0.1347±0.0025 | 18.220±0.001 | 0.15±0.02 | — | — |
| c | ≥1.38±0.05 MJ | 0.4737+0.0085 −0.0088 |
120.059±0.013 | 0.149±0.006 | — | — |
| d | ≥3.71+1.2 −0.51 MJ |
5.46+0.85 −0.40 |
4,696+1,133 −489 |
0.091+0.028 −0.018 |
— | — |
There is one confirmed exoplanet orbiting XO-2N. XO-2Nb, which is classified as a hot Jupiter, was discovered by the XO Telescope using the transit method around XO-2N in 2007. It was initially the only known planet in the system and was referred to as XO-2b.[3] A long-period variation in the radial velocity of XO-2N was detected in 2015, which could be explained by either a second planet or a stellar activity cycle. The stellar activity explanation is considered more likely,[6] and is further supported by a 2024 study.[11]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 0.597±0.021 MJ | 0.03668(9) | 2.615859719(54) | <0.006 | 87.47±0.37° | 1.033±0.023 RJ |
See also
Other systems with multiple planet-hosting stars:
Notes
References
- ^ Roman, Nancy G. (1987). “Identification of a constellation from a position”. Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP…99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). “Gaia Data Release 3. Summary of the content and survey properties”. Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A…674A…1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c d e Burke, Christopher J.; et al. (2007). “XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary”. The Astrophysical Journal. 671 (2): 2115–2128. arXiv:0705.0003. Bibcode:2007ApJ…671.2115B. doi:10.1086/523087. S2CID 13468914.
- ^ a b c d e Vallenari, A.; et al. (Gaia collaboration) (2023). “Gaia Data Release 3. Summary of the content and survey properties”. Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A…674A…1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ a b c Damasso, M.; et al. (2015). “The GAPS programme with HARPS-N at TNG. V. A comprehensive analysis of the XO-2 stellar and planetary systems”. Astronomy & Astrophysics. 575 A111. arXiv:1501.01424. Bibcode:2015A&A…575A.111D. doi:10.1051/0004-6361/201425332.
- ^ a b c Wang, Weilong; Gu, Shenghong; Wang, Xiaobin; Sun, Leilei; Lee, Byeong-Cheol; Kwok, Chi-Tai; Hui, Ho-Keung; Dou, Jiangpei; Xiang, Yue; Cao, Dongtao; Xu, Fukun (June 2025). “Observations and Studies on the Transiting Systems HAT-P-36, XO-2 and WASP-76”. The Astronomical Journal. 169 (6): 342. Bibcode:2025AJ….169..342W. doi:10.3847/1538-3881/add1de. ISSN 0004-6256.
- ^ a b “TYC 3413-210-1”. SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-28.
- ^ a b “TYC 3413-5-1”. SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-01-28.
- ^ a b Desidera, S.; et al. (2014). “The GAPS programme with HARPS-N at TNG. IV. A planetary system around XO-2S”. Astronomy and Astrophysics. 567 (6) L6. arXiv:1407.0251. Bibcode:2014A&A…567L…6D. doi:10.1051/0004-6361/201424339. S2CID 118567085.
- ^ a b c Ruggieri, A.; Desidera, S.; et al. (April 2024). “The GAPS Programme at TNG. LIII. New insights on the peculiar XO-2 system”. Astronomy & Astrophysics. 684: A116. arXiv:2401.17876. Bibcode:2024A&A…684A.116R. doi:10.1051/0004-6361/202348042.
Further reading
- Fernandez, Jose M.; et al. (2009). “The Transit Light Curve Project. XII. Six Transits of the Exoplanet XO-2b”. The Astronomical Journal. 137 (6): 4911–4916. arXiv:0903.2687. Bibcode:2009AJ….137.4911F. doi:10.1088/0004-6256/137/6/4911. S2CID 7113991.
- Narita, Norio; et al. (2011). “XO-2b: a Prograde Planet with a Negligible Eccentricity and an Additional Radial Velocity Variation”. Publications of the Astronomical Society of Japan. 63 (6): L67–L71. arXiv:1110.6136. Bibcode:2011PASJ…63L..67N. doi:10.1093/pasj/63.6.l67. S2CID 119269227.
- Sing, D. K.; et al. (2011). “Gran Telescopio Canarias OSIRIS transiting exoplanet atmospheric survey: detection of potassium in XO-2b from narrowband spectrophotometry”. Astronomy and Astrophysics. 527 A73. arXiv:1008.4795. Bibcode:2011A&A…527A..73S. doi:10.1051/0004-6361/201015579. S2CID 56545385.
External links
- NASA PlanetQuest: Planet race heats up: 1 month, 32 discoveries
- “XO-2”. Exoplanets. Archived from the original on 2016-03-03. Retrieved 2009-04-28.
